When you say "nicer" here, I'm assuming you mean a higher density screen.

With all products such as this, there are certain engineering and costs decisions that have to be made. Apple had very aggressive pricing goals with the iPad. Putting a screen with the same pixel density as the iPhone 4 would likely have pushed the cost of the device above the company's target, making it far too expensive for many people. A higher resolution screen would also require more horsepower, which the A4 chip may not have yet. (That's an assumption on my part and not necessarily a fact.) It could also be a drain on battery life, pushing the total number of hours well below the current 10. All this and more could have contributed to the screen that was used.

As it stands, I will side with those who say the screen is one of its strongest features. Most desktop and laptop computers don't boast a display as nice as this. That is definitely saying something.